A rinsing device of the kind mentioned above is known, for example, from EP 0 106 858 B1, where a rinsing device is described with a cylindrical rinsing chamber which has an anterior chamber part connectable to a measuring fluid container and which is configured to receive an immersion tube that contains a sensor and is coaxial with and movable along the longitudinal axis of the chamber. The immersion tube is axially movable between a retracted rest position and a deployed working position in order to bring the anterior part of the sensor into contact with the measuring medium in the measuring fluid container. The rinsing chamber has a rinsing area delimited by two ring grooves. The circumferential wall of the rinsing area is equipped with an inlet as well as an outlet for a rinsing medium. In its retracted rest position, the sensor is in the rinsing area where it can be treated with rinsing medium if desired.
The rinsing device described in EP 0 106 858 B1 is part of a probe-holder armature which is installed horizontally in the example shown, i.e., the longitudinal axis of the rinsing chamber is aligned substantially in the horizontal direction. In order to ensure that the rinsing medium is drained as completely as possible from the rinsing chamber, the probe-holder armature is connected to the measuring fluid container in such a way that the drainage outlet is directed downwards, so that the drain orifice is located at the lowest point of the rinsing area. However, if this probe-holder armature is installed vertically or even only close to a vertical position with the sensor extending downward, the rinsing medium can drain off only partially, as the portion of the rinsing medium collected below the drainage outlet will remain in the rinsing chamber. This is highly undesirable for a variety of reasons. For one, a rinse cycle of the sensor as a rule is not performed in one single step in which a single rinsing medium is introduced, but the rinse cycle consists in most cases of a sequence of operations which includes, e.g., a pre-rinse, a treatment with cleaning medium, a post-rinse, a blowing-out with air or a similar procedure, and in some cases a calibration of the sensor by means of appropriate calibration liquids. In a sequence of this kind, as little of the medium as possible should be left in the rinsing chamber after each operation. Furthermore, it should be kept in mind that when the immersion tube is deployed from the rest position into the measuring position, the parts of the immersion tube and the sensor that were in the rinsing area are now entering into the measuring fluid container where they come into contact with the measuring medium. If residual parts of the rinsing medium are taken along, the measuring medium can become contaminated or otherwise compromised.
A possible solution to avoid these problems is found in the probe holder armature according to CH 673 783 A5, which is designed especially for installation in a vertical position. It has a rinsing device that is formed of two rinsing chambers arranged behind each other. With this concept, individual parts of the device can be partitioned off by a kind of sluice-gate arrangement, so that the rinsing medium can be prevented from entering the measuring fluid container, while at the same time the measuring medium can be prevented from escaping into the outer parts of the probe-holder armature. However, the complexity and cost of this rinse chamber are a considerable drawback.